This proposal describes the first internally-geared, 7-Speed/Coaster-Brake Hub System for Manual Wheelchairs {MWCHS} with significant commercial potential since it can be retrofitted to most manual wheelchairs {MWC}to increase the wheelchair's function. The MWCHS has a total gear range of 284% and provides a mechanical advantage similar to the 10-Speed derailleur/sprocket system found on most bicycles. The general populations who will benefit from the MWCHS include: marginal pushers, persons with upper extremity pain and persons who wish to travel over long periods of time or over long distances. The MWCHS allows the operator the choice of either: 1. normal Single/Fixed Gear Travel, accessible by direct rotation of tires or (optional) tire handrims; or 2. electronically Shifted 7-Speed and Differential Coaster- Brakes, accessible by second set of handrims with forward or backward motion, respectively. Four primary areas of the research plan remain to be completed in a Phase I: 1. completion of MWCHS construction; 2. evaluation of user feedback, 3. preliminary testing of physiological efficiency; and 4. MWCHS fatigue testing.